An internal combustion engine includes combustion chambers, each having a controllable intake valve opening and closing an intake port, a controllable exhaust valve opening and closing an exhaust port, a piston displaceable back and forth in the combustion chamber between a top dead center and a bottom dead center, and a fuel injector. The engine further including an intake manifold connected to the intake port of each combustion chamber. The engine can be operated in a low load mode, wherein each combustion chamber is driven in four-stroke operation including a 720 crank angle degrees cycle, and opens the intake port during the exhaust stroke, the intake port starting to open in 610-690 CAD, closing the exhaust port during the exhaust stroke, becoming fully closed in 630-710 CAD, forcing exhaust gas into the intake manifold by the piston, and mixing fuel and exhaust gas in the intake manifold.

An internal combustion engine includes combustion chambers, each having a controllable intake valve opening and closing an intake port, a controllable exhaust valve opening and closing an exhaust port, a piston displaceable back and forth in the combustion chamber between a top dead center and a bottom dead center, and a fuel injector. The engine further including an intake manifold connected to the intake port of each combustion chamber. The engine can be operated in a low load mode, wherein each combustion chamber is driven in four-stroke operation including a 720 crank angle degrees cycle, and opens the intake port during the exhaust stroke, the intake port starting to open in 610-690 CAD, closing the exhaust port during the exhaust stroke, becoming fully closed in 630-710 CAD, forcing exhaust gas into the intake manifold by the piston, and mixing fuel and exhaust gas in the intake manifold.

A control system of a compression-ignition engine which performs SPCCI combustion in which mixture gas is ignited with a spark plug to be partially combusted by SI combustion and the rest of mixture gas self-ignites to be combusted by CI combustion, is provided. When the engine is operated at least in a given first operating range, a controller of the device controls a variable intake mechanism so that an A/F lean environment where an air-fuel ratio in a cylinder becomes higher than a stoichiometric air-fuel ratio is formed, while causing the spark plug to perform spark ignition at a given timing so that the mixture gas combusts by SPCCI combustion, and controls so that, under the same engine load condition, an intake valve close timing is more retarded as the engine speed decreases, within a range where an amount of air inside the cylinder decreases by retarding the close timing.

A method for controlling intake and exhaust valves of an engine may include: determining, by a controller, a target opening duration of the intake and exhaust valves based on an engine load and an engine speed; modifying, by an intake continuous variable valve duration (CVVD) device and by an exhaust CVVD device, current opening and closing timings of the intake valve and/or exhaust valve based on the target opening duration of the valves; and advancing or retarding, by the intake and/or exhaust CVVD devices, the current opening timing of the intake and exhaust valves while simultaneously retarding or advancing the current closing timing of the intake and exhaust valve by a predetermined value based on the target opening duration.

A control system of a compression-ignition engine which performs SPCCI combustion in which mixture gas is ignited with a spark plug to be partially combusted by SI combustion and the rest of mixture gas self-ignites to be combusted by CI combustion, is provided. When the engine is operated at least in a given first operating range, a controller of the device controls a variable intake mechanism so that an A/F lean environment where an air-fuel ratio in a cylinder becomes higher than a stoichiometric air-fuel ratio is formed, while causing the spark plug to perform spark ignition at a given timing so that the mixture gas combusts by SPCCI combustion, and controls so that, under the same engine load condition, an intake valve close timing is more retarded as the engine speed decreases, within a range where an amount of air inside the cylinder decreases by retarding the close timing.

A method for controlling intake and exhaust valves of an engine may include: determining, by a controller, a target opening duration of the intake and exhaust valves based on an engine load and an engine speed; modifying, by an intake continuous variable valve duration (CVVD) device and by an exhaust CVVD device, current opening and closing timings of the intake valve and/or exhaust valve based on the target opening duration of the valves; and advancing or retarding, by the intake and/or exhaust CVVD devices, the current opening timing of the intake and exhaust valves while simultaneously retarding or advancing the current closing timing of the intake and exhaust valve by a predetermined value based on the target opening duration.

A method is provided for controlling a filling (rl) of an internal combustion engine (2) including the camshaft phase adjustment in the case of a predefined setpoint filling (rlsol), including the following steps: carrying out the filling control based on an indicated pressure difference for obtaining a control variable (.sub.Fuereg) for setting an air mass supply to the internal combustion engine (2); and ascertaining the indicated pressure difference (p.sub.SR) as a difference between a predicted intake manifold pressure (p.sub.srpred) and an actual intake manifold pressure (p.sub.SR), the predicted intake manifold pressure (p.sub.srpred) corresponding to an intake manifold pressure which is necessary for reaching the setpoint filling (rlsol) at an aspiration curve which is predicted for a predefined time constant ().